This disclosure relates generally to equipment utilized and operations performed in conjunction with a subterranean well and, in an example described below, more particularly provides for downhole orientation sensing with a nuclear spin gyroscope.
It is frequently desirable to be able to sense the orientation of well tools, instruments, etc. in a well. For example, in some logging operations, sensitive tiltmeters and microseismic sensors are used. The orientation of these sensors in a well needs to be known, in order to relate sensed parameters to their positions in space relative to the well.
Various mechanical and optical gyroscopes, gyrocompasses, etc. are known in the art, but each of these suffers from one or more deficiencies. These deficiencies can include mechanical complexity, the use of rapidly spinning components which can interfere with sensitive tiltmeters and microseismic instruments, lack of ability to find a true north direction on its own, large dimensions, low acceptable operating temperature, inability to operate effectively in a ferrous casing, etc.
Therefore, it will be appreciated that improvements are needed in the art of downhole orientation sensing. These improvements would be useful in logging and other operations in which the orientation of downhole instruments, well tools, etc. is desired.